libFuzzer: prevent irrelevant strings from leaking into auto-dictionary

This is a fix for bug 37047.

https://bugs.llvm.org/show_bug.cgi?id=37047

Implemented by basically reversing the logic. Previously all strings
were considered, with some operations excluded. Now strings are excluded
by default, and only strings during the CB considered.

Patch By: pdknsk

Differential Revision: https://reviews.llvm.org/D48800

llvm-svn: 337296

1 files changed, 8 insertions, 6 deletions

diff --git a/compiler-rt/lib/fuzzer/FuzzerLoop.cpp b/compiler-rt/lib/fuzzer/FuzzerLoop.cpp
index ba61c15f01b..a2d53ee48db 100644
--- a/compiler-rt/lib/fuzzer/FuzzerLoop.cpp
+++ b/compiler-rt/lib/fuzzer/FuzzerLoop.cpp
@@ -43,6 +43,8 @@ thread_local bool Fuzzer::IsMyThread;
 
 SharedMemoryRegion SMR;
 
+bool RunningUserCallback = false;
+
 // Only one Fuzzer per process.
 static Fuzzer *F;
 
@@ -243,7 +245,7 @@ void Fuzzer::CrashCallback() {
 }
 
 void Fuzzer::ExitCallback() {
-  if (!RunningCB)
+  if (!RunningUserCallback)
     return; // This exit did not come from the user callback
   if (EF->__sanitizer_acquire_crash_state &&
       !EF->__sanitizer_acquire_crash_state())
@@ -277,7 +279,7 @@ void Fuzzer::AlarmCallback() {
   if (!InFuzzingThread())
     return;
 #endif
-  if (!RunningCB)
+  if (!RunningUserCallback)
     return; // We have not started running units yet.
   size_t Seconds =
       duration_cast<seconds>(system_clock::now() - UnitStartTime).count();
@@ -451,9 +453,9 @@ void Fuzzer::CheckForUnstableCounters(const uint8_t *Data, size_t Size) {
     ScopedEnableMsanInterceptorChecks S;
     UnitStartTime = system_clock::now();
     TPC.ResetMaps();
-    RunningCB = true;
+    RunningUserCallback = true;
     CB(Data, Size);
-    RunningCB = false;
+    RunningUserCallback = false;
     UnitStopTime = system_clock::now();
   };
 
@@ -558,9 +560,9 @@ void Fuzzer::ExecuteCallback(const uint8_t *Data, size_t Size) {
     AllocTracer.Start(Options.TraceMalloc);
     UnitStartTime = system_clock::now();
     TPC.ResetMaps();
-    RunningCB = true;
+    RunningUserCallback = true;
     int Res = CB(DataCopy, Size);
-    RunningCB = false;
+    RunningUserCallback = false;
     UnitStopTime = system_clock::now();
     (void)Res;
     assert(Res == 0);